In my roughly 20 years working in the federal policy arena, few things have become clearer to me than the importance of data. If something is not counted, it is neither seen nor understood. For all intents and purposes, it does not exist.

That’s why the Trump administration’s decision not to collect data on the lives of lesbian, gay, bisexual and transgender Americans threatens these communities in ways that are both symbolic and practical.

It was announced Tuesday that the United States Census Bureau director, John H. Thompson, had abruptly stepped down from his job, drawing national attention to the agency. But I and others in the L.G.B.T. community have been focused on the bureau’s work for months — for reasons related not to its leadership, but to the collection of information. In March, when it published a list of planned subjects for data collection that included a proposed question on these topics, many of us were optimistic. After years of advocating this very change, there was a possibility that we might be more fully counted. But that cheer was to be short lived. The Census Bureau quickly clarified that it had “inadvertently listed sexual orientation and gender identity as a proposed topic” and made changes to the online document within hours.

During the same month, the Department of Health and Human Services eliminated questions about L.G.B.T. people from drafts of two critical surveys: the National Survey of Older Americans Act Participants, which helps inform social and nutritional support programs for seniors; and the Centers for Independent Living Annual Program Performance Report, which helps inform programs designed to allow people with disabilities to live independently.

This is concerning, because sound policy relies on good data, which in turn relies on robust data collection. The federal government needs to understand the